The decision, which follows a campaign by Qatari financial authorities to persuade foreign investors that they have free access to riyal currency, is likely to please Doha’s stock market.

Two weeks ago, MSCI had said it would consider using offshore rates because economic sanctions against Qatar had made it more difficult for foreigners to obtain riyal onshore. Such a step could have reduced the weightings of Qatari stocks in MSCI’s emerging market index.

Saudi Arabia, the United Arab Emirates, Bahrain and Egypt cut diplomatic and transport ties with Qatar in June. As a result many Gulf and other foreign banks reduced their business with Qatari banks, distorting the foreign exchange market, where onshore and offshore rates diverged.

While the riyal traded very close to its peg of 3.64 against the U.S. dollar onshore, it changed hands as low as 3.8950 offshore on the Reuters conversational dealing platform.

Qatar’s central bank responded by saying it was committed to providing all currency requirements of investors at onshore exchange rates, and the gap with offshore rates has narrowed greatly in the last few days.

MSCI said on Tuesday that it would keep using onshore rates for now, but would “continue to closely monitor the accessibility of the Qatari FX market and may potentially decide to switch to the offshore FX rates in the future should the situation materially deteriorate”.

While 90 percent of feedback from investors which MSCI received before the central bank’s pledge favoured the proposal to switch to offshore rates, over 50 percent of participants changed their views after the pledge, MSCI said.

However, it added that because the gap between onshore and offshore rates was still seen as an issue by investors, it might switch to offshore rates in future without further public consultation if the gap widened persistently. (Reporting by Andrew Torchia; Editing by Sandra Maler and Diane Craft)